public class j1403 {
    public static void main(String[] args) {
        int count = 0;
        for(int i = 1;i <= 100; i++){
            int tmp = i;
            for(int j = 1;j <= 2;j++) {
                if (tmp % 10 == 9) {
                    tmp /= 10;
                    count++;
                }
            }
        }
        System.out.println(count);
    }
}
